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Background <p>With the rapid advancement of digital technologies, digital intraoral scanning offers potential advantages for post-and-core impressions. However, its accuracy in relation to the complete spectrum of clinically relevant post space diameters, particularly smaller conservative preparations, requires comprehensive evaluation. This in vitro study aimed to systematically assess the accuracy of direct digital impressions compared to conventional impressions across four diameters and varying depths.</p> Methods <p>Forty extracted single-rooted teeth were divided into four groups (<i>n</i> = 10/group) based on post space diameter: 1.0, 1.5, 2.0, and 2.5&#xa0;mm. Each specimen was scanned using an intraoral scanner (TRIOS 5). Silicone impressions scanned with an extraoral scanner served as the reference. Root mean square (RMS) deviations were analyzed at four depths (1.65, 5.0, 7.0, 9.0&#xa0;mm). Statistical analysis employed linear mixed-effects models.</p> Results <p>The scanner completely failed to capture data for the 1.0&#xa0;mm diameter at depths ≥ 7&#xa0;mm and for the 1.5&#xa0;mm diameter at 9&#xa0;mm. A significant diameter-by-depth interaction was found (<i>p</i> &lt; 0.001). For diameters ≥ 1.5&#xa0;mm and depths ≤ 7&#xa0;mm, accuracy was clinically acceptable. At the 9&#xa0;mm depth, the 2.0&#xa0;mm and diameter group showed significantly higher deviation and critically high variability (135.0 ± 79.5&#xa0;μm, CV 59.0%), while the 2.5&#xa0;mm group maintained superior and more reliable accuracy (41.4 ± 28.8&#xa0;μm).</p> Conclusions <p>Direct intraoral scanning is a viable option for post spaces with a diameter ≥ 1.5&#xa0;mm and depth ≤ 7&#xa0;mm. Its application is strictly limited in narrow canals (≤ 1.5&#xa0;mm). For deep preparations (9&#xa0;mm), a minimum diameter of 2.0&#xa0;mm allows data capture but with poor reliability, whereas a diameter ≥ 2.5&#xa0;mm ensures acceptable and predictable accuracy. Clinical adoption requires careful consideration of these diameter- and depth-dependent performance boundaries.</p>

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Evaluation of the accuracy of direct digital impressions versus conventional silicone impressions for post-and-core with different root space diameters: a preliminary study in vitro

  • 期刊论文

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  • 发表日期：

    2026年1月8日

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  • Jiyuan Shen,
  • Sifan Chen,
  • Ruizhen Chen,
  • Zhiqiang Zheng,
  • Jie Lin

摘要

Background

With the rapid advancement of digital technologies, digital intraoral scanning offers potential advantages for post-and-core impressions. However, its accuracy in relation to the complete spectrum of clinically relevant post space diameters, particularly smaller conservative preparations, requires comprehensive evaluation. This in vitro study aimed to systematically assess the accuracy of direct digital impressions compared to conventional impressions across four diameters and varying depths.

Methods

Forty extracted single-rooted teeth were divided into four groups (n = 10/group) based on post space diameter: 1.0, 1.5, 2.0, and 2.5 mm. Each specimen was scanned using an intraoral scanner (TRIOS 5). Silicone impressions scanned with an extraoral scanner served as the reference. Root mean square (RMS) deviations were analyzed at four depths (1.65, 5.0, 7.0, 9.0 mm). Statistical analysis employed linear mixed-effects models.

Results

The scanner completely failed to capture data for the 1.0 mm diameter at depths ≥ 7 mm and for the 1.5 mm diameter at 9 mm. A significant diameter-by-depth interaction was found (p < 0.001). For diameters ≥ 1.5 mm and depths ≤ 7 mm, accuracy was clinically acceptable. At the 9 mm depth, the 2.0 mm and diameter group showed significantly higher deviation and critically high variability (135.0 ± 79.5 μm, CV 59.0%), while the 2.5 mm group maintained superior and more reliable accuracy (41.4 ± 28.8 μm).

Conclusions

Direct intraoral scanning is a viable option for post spaces with a diameter ≥ 1.5 mm and depth ≤ 7 mm. Its application is strictly limited in narrow canals (≤ 1.5 mm). For deep preparations (9 mm), a minimum diameter of 2.0 mm allows data capture but with poor reliability, whereas a diameter ≥ 2.5 mm ensures acceptable and predictable accuracy. Clinical adoption requires careful consideration of these diameter- and depth-dependent performance boundaries.